1. Field of the Invention
This invention relates generally to the field of optical image transfer. In particular, this invention relates to a wide angle image transfer system capable of transforming images of up to 360.degree. in conjunction with the taking and projection of pictures.
2. Description of the Prior Art
In many training situations the presentation of an external environment is a necessity in order for the trainee to perceive visual cues and thereby learn to take actions or manipulate training equipment to maximum advantage for a given training situation. A particularly useful approach to realism in display is to generate a 350.degree. wide-angle presentation to produce the effect of the observer being in the center of scene activity.
U.S. Pat. No. 4,012,126 by Gottfried R. Rosendahl and Wiley V. Dykes discloses an optical transfer system for 360.degree. image transfer in which spaced primary and secondary hyperbolically surfaced mirrors are combined with a refractive lens system and are held in spaced relationship by a transparent envelope having inner and outer surfaces generated from the near focal point of the primary mirror. The primary mirror coincides with the entrance pupil of the system in order to avoid aberrations by the envelope within a pencil of rays originating from an object or image point and particularly between rays originating at different object or image points.
The lens system disclosed in the above patent was determined to be susceptible to damage from thermal shock and did not adequately deal with chromatic aberrations. In order to correct these deficiencies, U.S. patent application Ser. No. 265,874 by Gottfried R. Rosendhal and Wiley V. Dykes, filed May 21, 1981 now U.S. Pat. No. 4,395,093, disclosed a modified lens system incorporating four lens groups of positive and negative refracting power to achieve the required visual clarity. The modified lens utilizes a number of lenses which require rather exotic glasses, thus yielding a rather expensive apparatus.